Blister Pack with Built-In Cutting Ledges

ABSTRACT

This invention provides a blister pack comprising a base sheet having a plurality of blisters formed therein, each of which has an opening and is configured for containing a unit dose of a deformable or fragile product, with a lid sheet attached to said base sheet for covering the openings of said blisters. The blister pack further comprises a reinforcing sheet with cut-out sections that form ledges near said blister openings. Such ledges can be used for cutting the lid sheet at said blister openings and releasing the unit doses of said deformable or fragile product.

FIELD OF THE INVENTION

This invention relates to blister packs, especially the push-through type of blister packs for containment and dispensing of deformable or fragile articles.

BACKGROUND OF THE INVENTION

Blister packs have been used for containing various products such as medicine, food, cosmetics, personal cleansing products or laundry care products, while protecting such products from damage or exposure. Unit doses of such products are stored in readily accessible, individually sealed compartments (i.e., blisters) of such blister packs. Typically, a back sheet is used to seal the individual compartments in the blister packs. Each compartment can then be opened independent of any other compartments in such blister packs.

In some blister packs, the back sheet can be peeled back to expose the contents of individual compartments. However, it is not uncommon for an area of such peelable sheet to tear away in such a manner as to expose more than one compartment, leaving the contents in the other compartments (other than the one intended to be opened) at risk for contamination. Therefore, such peelable type of blister packs may be undesirable.

In other blister packs, the back sheet is frangible and can be broken when the contents of individual compartments are pushed against it by application of external force thereon. Blister packs with such frangible back sheets are referred to as the “push-through type”, and they can be readily used for containing solid and rigid products that are structurally sound, such as pills or lozenges. However, when the products to be contained and dispensed are elastically deformable or fragile, it is difficult to push through such products to break the back sheet without damaging or severely deforming the product. Therefore, the push-through type blister packs may be unsuitable for housing and dispensing deformable or fragile products or contents.

In certain push-through type of blister packs, internal or external openers or cutters are provided for piecing or cutting the back sheet to release the contents of individual compartments. For example, U.S. Pat. No. 5,816,404 discloses a blister pack with an opener that is supported by a frame over the blister opening, and such opener can be displaced downwardly to first piece a back sheet that covers the blister opening and then to remove such back sheet by rotation. For another example, U.S. Pat. No. 6,443,307 discloses a blister pack with dome-shaped blisters sealed by a lower membrane, while each dome-shaped blister contains an annular-shaped internal cutter that can be used to cut through the lower member by simply depressing the dome-shaped blister. However, such known internal or external cutters or openers tend to have complex structures, and to make them requires significant additional materials and complicated processing steps, which can be cost-prohibitive for certain consumer goods such as cosmetics, personal cleansing products or laundry care products.

Therefore, there is a need for new blister pack designs that are particularly suitable for housing and dispensing deformable or fragile articles, which are both easy to open and easy/inexpensive to make.

SUMMARY OF THE INVENTION

The present invention provides push-through type of blister packs with built-in ledges formed by at least one reinforcing sheet, which are both easy/inexpensive to make and effective for cutting the back or lid sheet that seals the blisters. Such built-in ledges enable easy release of products/contents from the blister packs with minimal damage or deformation, so are particularly suitable for use with deformable or fragile products/contents, more preferably a product/content that is elastically deformable.

The present invention in one aspect provides a package for containing and dispensing at least one article, which comprises:

-   -   a) a base sheet having at least one depression formed therein         for containing an article, the depression having an opening;     -   b) a lid sheet attached to said base sheet to cover the opening         of said at least one depression; and     -   c) a reinforcing sheet attached to the lid sheet at a side         opposite from said base sheet, said reinforcing sheet having at         least one cut-out section that overlaps with but offsets from         the opening of said depression so that a portion of the         reinforcing sheet forms a ledge near the opening of said         depression for cutting the lid sheet and releasing the article         from said depression.

The present invention in another aspect provides a blister pack for containing and dispensing multiple unit doses of a product, which comprises:

-   -   a) a base sheet having a plurality of blisters formed therein,         each of which has an opening and is configured for containing a         unit dose of said product therein;     -   b) a lid sheet attached to said base sheet to cover the openings         of said blisters; and     -   c) a reinforcing sheet attached to the lid sheet at a side         opposite from said base sheet, said reinforcing sheet having a         plurality of cut-out sections, each of which overlaps with but         offsets from one of the blister openings so that portions of the         reinforcing sheet form a plurality of ledges that each is near         one of the blister openings for cutting the lid sheet at said         opening and releasing the unit does of the product.

Such package or blister pack with the reinforcing sheet is easy/inexpensive to make, while the cutting ledges formed by the cut-out sections in the reinforcing sheet are simple yet structurally sound/robust. More importantly, they are effective for cutting the lid sheet with minimal impact/force on the article or product contained therein during release.

Further objects and advantages of the present invention will become apparent in the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a prior art blister pack configured for containing and dispensing a solid and rigid product.

FIG. 2 is a cross-sectional view illustrating the difficulties encountered when using the prior art blister pack of FIG. 1 to contain and dispense a deformable or fragile product.

FIG. 3 is a cross-sectional view of a blister pack according to one embodiment of the present invention.

FIG. 4A is a perspective view of a blister pack according to one embodiment of the present invention, which contains a top reinforcing sheet and a bottom reinforcing sheet.

FIG. 4B is a top view of the top and bottom reinforcing sheets of FIG. 4A.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a new push-through type of blister pack or package.

In a conventional blister pack of the push-through type, as shown in FIG. 1, a substantially impermeable plastic material 1 is used to form multiple blisters 2, each of which defines a cavity or depression for the containment of a solid and rigid tablet 4 therein. The openings 3 of the blisters 2 are closed or sealed by a rupturable lid sheet 5 formed of a metal foil, which is thin enough so that when the blisters 2 are compressed by the application of an external force F into shape 2A, the metal foil lid sheet 5 will break or rupture. Consequently, the solid and rigid tablet 4 will be forced out of the compressed blisters 2A.

However, when such conventional blister pack as described hereinabove is used to house and dispense an elastically deformable product 4′, the external force F applied onto the blister cavity 2 will mostly be absorbed by the product 4′ to effectuate its deformation into the compressed form 4″, instead of being applied to the metal foil lid sheet 5 to effectuate its rupture, as shown in FIG. 2. In order to eventually rupture the lid sheet 5 and to release the product 4″, significantly greater external force F needs to be applied now. The application of greater external force F may cause the entire blister pack to bend, making the force transfer less efficient and even compromising the structural integrity of the blister pack itself. Ultimately, the need of a greater external force F to rupture the lid sheet (de-blistering force) may result into either the impossibility to withdraw the product from the blister pack or in severe and potentially irreversible deformation of the product 4″, and in some cases even lead to significant damages of such product.

In order to solve the above technical problem, the present invention provides a package or blister pack with a reinforcing sheet attached to the lid sheet at a side opposite to the blisters. Such a reinforcing sheet helps to improve the overall structural integrity of the blister pack against bending under excessive external force. More importantly, such reinforcing sheet forms cutting ledges near the openings of the blisters, and such ledges are particularly effective in converting external force applied generally to the lid sheet into a highly localized cutting force for rupturing the lid sheet along such ledges, thus minimizing the de-blistering force.

For example, FIG. 3 is a cross-sectional view of a package 10 according to a specific embodiment of the present invention, which comprises a base sheet 20 having one or more depressions or blisters 22A and 22B formed therein, for containing one or more articles or unit doses of products 23A and 23B. The base portion of such base sheet 20 is preferably substantially planar. The depressions or blisters 22A and 22B each has an opening near the base portion of the base sheet 20. A substantially planar lid sheet 30 is attached to the base portion of the base sheet 20, e.g., by heat sealing, adhesives, or any other suitable attachment mechanisms, to cover the openings of the depressions or blisters 22A and 22B, thereby enclosing and sealing the articles or products 23A and 23B inside the depressions or blisters 22A and 22B. A substantially planar reinforcing sheet 40 is attached to the lid sheet 30 at a side that is opposite from the base sheet 20, e.g., by heat sealing, adhesive, or any other suitable attachment mechanisms. The reinforcing sheet 40 comprises one or more cut-out sections 42A and 42B, which overlap with but offset from the openings of the depressions or blisters 22A and 22B, thereby forming one or more ledges 44A and 44B near the blister openings. Such ledges 44A and 44B function to localize any external force applied to the lid sheet 30 through compression of the blisters 22A and 22B and/or the articles or products 23A and 23B, and such localized force is then focused for cutting the lid sheet 30 near the blister openings. Because the external force applied to the lid sheet 30 is so localized, less force is needed for cutting the lid sheet 30 and releasing the articles/products 23A and 23B from the blisters 22A and 22B. Correspondingly, the articles/products 23A and 23B are subject to less deformation or impact, and the risk of irreversible deformation or damages is significantly reduced.

Further, the use of such a substantially planar reinforcing sheet 40 to structurally reinforce the package 10 and to provide built-in cutting ledges 44A and 44B for rupturing the lid sheet 30 adds little or no additional cost and complexity to the manufacturing process, and it requires minimal additional capital investment. More importantly, such built-in cutting ledges 44A and 44B are structurally integral with other components of the package 10, and they are unlikely to be damaged or cause damages to the articles or products 23A and 23B contained in the package 10 or to other components during shipment or transportation.

The depressions or blisters according to the present invention may be of any suitable shape, e.g., cubical, rectangular, cylindrical, semi-spherical or dome-shaped. It is preferred that the depressions or blisters have round edges, and more preferably the depressions or blisters have a semi-spherical or dome shape (as shown in 22A and 22B of FIG. 3), which allows for easy compression thereof under impact of external forces. As known in the art, as the blister cavity is depressed, the pressure within the cavity increases. This extra pressure helps expel the article from the blister. Preferably but not necessarily, the package 10 may further comprise an additional reinforcing sheet 50, which is attached to the base sheet 20 at a side opposite from the lid sheet 30. The additional reinforcing sheet 50 comprises one or more additional cut-out sections that are configured for accommodating the depressions or blisters 22A and 22B, i.e., the depressions or blisters 22A and 22B can fit through the additional cut-out sections in such additional reinforcing sheet 50, as shown in FIG. 3. Such additional reinforcing sheet 50 provides additional structural reinforcement for the package 10 from its back side. Such additional reinforcing sheet 50 can be easily formed from the same sheet of paper laminate or paper/polymer laminate used for forming the aforementioned reinforcing sheet 40, e.g., by folding such sheet of paper laminate or paper/polymer laminate over into two halves.

FIG. 4A shows a perspective view of a blister pack 100, which includes a base sheet (not shown) having a plurality of blisters 122A and 122B formed therein, each of which has an opening (not shown) and is configured for containing a unit dose of a deformable or fragile product (not shown). The blister pack 100 further comprises a lid sheet (not shown) attached to said base sheet (not shown) from beneath to cover the openings (not shown) of the blisters 122A and 122B. Preferably each cavity of the blister pack is spaced by at least 2 mm, even more preferably above 3 mm and most preferred above 4 mm to allow adequate sealing between the base sheet and the lid sheet, thus minimizing the risk of exposing each adjacent cavity when the product is pushed out. In any case, the cavities of the blister pack may be spaced to allow a finger to press on each of them individually without interference. Similarly, the margin of the base sheet and the lid sheet should have a seal area preferably above 2 mm, even more preferably above 3 mm and most preferred above 4 mm A top reinforcing sheet 150 is attached to the base sheet (not shown) from above, while such top reinforcing sheet 150 contains a plurality of top cut-out sections (not shown) configured for accommodating the blisters 122A and 122B, i.e., by allowing them to come therethrough. A bottom reinforcing sheet 140 is attached to the lid sheet (not shown) from beneath, said bottom sheet 140 containing a plurality of cut-sections 142A and 142B, each of which overlaps with but offsets from one of the blister openings (not shown) so that portions of the bottom reinforcing sheet 140 form a plurality of ledges 144A and 144B. Each of the ledges 144A and 144B is near one of the blister openings (not shown) for cutting the lid sheet (not shown) at the blister opening and releasing a unit dose of the deformable or fragile product (not shown). FIG. 4B shows a top view of only said top reinforcing sheet 150 and the bottom reinforcing sheet 140 (not directly visible). The top reinforcing sheet 150 comprises multiple top cut-out sections 152A and 152B that are configured to accommodate the blisters 122A and 122B previously shown in FIG. 4A. The bottom reinforcing sheet 140 (not visible here) contains multiple bottom cut-out sections 142A and 142B that overlap with but offset from the blister openings (not shown here) and correspondingly the top cut-out sections 152A and 152B. As a result, portions of the bottom reinforcing sheet 140 (not visible) for multiple ledges 144A and 144B that can be seen through the top reinforcing sheet 150, and such ledges 144A and 144B enable localization of external forces for cutting the lid sheet that seals the blister openings.

The article or product to be housed by the package or blister pack of the present invention can be of any form, e.g., solid, semi-solid, powder, paste, liquid, gel, foam, and the like. Preferably, such article or product is deformable or fragile. More preferably, such article or product is elastically deformable, i.e., it can be deformed under stress but can eventually return to the original shape with little or no change in shape when the stress is removed. Most preferably, such article or product is characterized by a Young's Modulus of no more than about 5, preferable from about 0.01 to about 1, more preferably from about 0.01 to about 0.5, most preferably from about 0.01 to about 0.1. In a particularly preferred embodiment of the present invention, such article or product is flexible, porous and dissolvable, which may contain one or more water-soluble polymer in combination with one or more functional ingredients.

The article or product of the present invention may have any shape or size suitable for its intended use, as long as it is configured for passing through the blister opening and the cut-out section in the reinforcing sheet after the lid sheet has been broken or ruptured by the ledge, while itself will not be cut or damaged by the ledge. To maximize the force transfer during dispensing preferably the article should have a footprint area smaller than 600 mm², more preferably below 400 mm² and even more preferably below 200 mm² and a thickness preferably above 6 mm, more preferably above 10 mm and even more preferably above 15 mm. The base sheet of the present invention is preferably a flexible yet structurally sound sheet with a substantially planar base portion and one or more depressions or blisters formed therein.

The base sheet may be formed of any suitable materials, including but not limited to: plastic materials, plastic laminates, and the like. The base sheet materials should be compatible with the product stored inside and have a low water-vapor transmission rate (depending on the specific application). Suitable plastic materials for making the base sheet of the present invention may be selected from the group consisting of polypropylene (PP), copolymers and terpolymers of propylene, polyethylene (PE), polyvinyl chloride (PVC), polyvinyl dichloride (PVdC), copolymers and terpolymers of vinyl chloride and/or vinyl dichloride, poly-chloro-tri-fluoro-ethylene (PCTFE), cyclic olefin copolymers (COC) and combinations thereof. In a particularly preferred embodiment of the present invention, the base sheet is formed by a transparent PP material.

The base sheet may be characterized by a thickness at its base portion (i.e., base thickness) ranging from about 100 microns to about 1000 microns, preferably from about 200 microns to about 800 microns, more preferably from about 300 microns to about 600 microns, most preferably about 500 microns. The thickness of such base sheet at the depression or blister portion (i.e., depression thickness or blister thickness) is preferably significantly smaller than that of its base thickness, so as to enable easy deformation or compression of the depressions or blisters without compromising the overall structural integrity of the blister pack. For example, the depression/blister thickness of the base sheet may be no more than ¾, preferably no more than about ⅗, more preferably no more than about ½ of its base thickness. Depressions or blisters with such reduced depression thickness are easily deformable and can be deformed/compressed downwardly toward the blister openings when an external force is applied, while offering sufficient strength to prevent denting or damage during distribution or package handling.

The lid sheet as used in the present invention may be substantially planar and is preferably coterminous with the base sheet. Such a lid sheet can be attached to the base sheet by any attachment mechanisms, e.g., heat-sealing, adhesives, stamping, pressure-sealing, and the like. Preferably, the lid sheet has a heat-sealable coating and is heat-sealed to the base sheet. More preferably, the heat-sealable coating is applied by lacquer and should have low density to minimize the film stretching and enhance its pierce-ability. Such a lid sheet may be formed of any suitable materials, such as aluminum foil, aluminum laminates, polymer laminate such as polyester laminates, polymer/aluminum laminates (especially polyester/aluminum laminates), paper, paper/aluminum laminates, and combinations thereof. Preferably, such lid sheet is soft or hard tempered aluminum foil or aluminum laminate. More preferably, the aluminum foil should be hard tempered with a thickness ranging from 12 to 30 microns, and most preferably between 15 to 25 microns. In a particularly preferred embodiment, the lid sheet is a hard aluminum of 20 micron.

The reinforcing sheets as used in the present invention may be formed of any suitable materials, including but not limited to paper laminates and paper/polymer laminates. Such reinforcing sheets preferably are thick enough to provide sufficient structural support for the blister pack of the present invention, i.e., to avoid significant bending of such blister pack during opening of the blisters and dispensing of the contents therein. Further, thicker reinforcing sheets provide stronger cutting ledges that can localize the cutting force more effectively.

Preferably, the reinforcing sheets of the present invention have a thickness (i.e., measured at a location away from the cut-out sections) ranging from about 0.5 mm to about 2 mm, preferably from about 0.7 mm to about 1.5 mm, more preferably from about 0.8 mm to about 1.2 mm More preferably, the blister pack of the present invention comprises both the top and bottom reinforcing sheets, which are formed by folding a single paper laminate (preferably with a polymer coating thereon) into two halves and then stamped or punched to form the corresponding cut-out sections thereon.

The cutting ledges formed by the offset portions of the bottom reinforcing sheet preferably have a semi-circular or arched shape, similar to those shown in FIGS. 4A and 4B. Such semi-circular or arched ledges are more effective for localizing the cutting force and cutting the lid sheet (in comparison with ledges that form a full or complete circle). It is also possible to provide ledges with sharp edges or even serrate edges to further improve the cutting effect.

The dimensions and values disclosed herein are not to be understood as being strictly limited to the exact numerical values recited. Instead, unless otherwise specified, each such dimension is intended to mean both the recited value and a functionally equivalent range surrounding that value. For example, a dimension disclosed as “40 mm” is intended to mean “about 40 mm.”

Every document cited herein, including any cross referenced or related patent or application and any patent application or patent to which this application claims priority or benefit thereof, is hereby incorporated herein by reference in its entirety unless expressly excluded or otherwise limited. The citation of any document is not an admission that it is prior art with respect to any invention disclosed or claimed herein or that it alone, or in any combination with any other reference or references, teaches, suggests or discloses any such invention. Further, to the extent that any meaning or definition of a term in this document conflicts with any meaning or definition of the same term in a document incorporated by reference, the meaning or definition assigned to that term in this document shall govern.

While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention. 

What is claimed is:
 1. A package for containing and dispensing at least one article, comprising: a) a base sheet having at least one depression formed therein for containing an article, the depression having an opening; b) a lid sheet attached to said base sheet to cover the opening of said at least one depression; and c) a reinforcing sheet attached to the lid sheet at a side opposite from said base sheet, said reinforcing sheet having at least one cut-out section that overlaps with but offsets from the opening of said depression so that a portion of the reinforcing sheet forms a ledge near the opening of said depression for cutting the lid sheet and releasing the article from said depression.
 2. The package of claim 1, wherein said article is elastically deformable.
 3. The package of claim 1, wherein said article has a shape configured for passing through said cut-out section of the reinforcing sheet without being cut by the ledge.
 4. The package of claim 1, wherein the base sheet comprises a material selected from the group consisting of polypropylene, a copolymer propylene, a terpolymer of propylene, polyethylene, polyvinyl chloride, polyvinyl dichloride, a copolymer of vinyl chloride, a copolymer of vinyl dichloride, a terpolymer of vinyl chloride, a terpolymer of vinyl dichloride, poly-chloro-tri-fluoro-ethylene, a cyclic olefin copolymer, and combinations thereof.
 5. The package of claim 1, wherein said base sheet has a base thickness of about 100 microns to about 1000 microns.
 6. The package of claim 1, wherein said base sheet has a depression thickness that is no more than about ⅗ of its base thickness.
 7. The package of claim 1, wherein said depression is deformable so that it deforms downwardly toward the opening when an external force is applied to said depression.
 8. The package of claim 1, wherein the depression has a dome shape.
 9. The package of claim 1, wherein the lid sheet comprises a material selected from the group consisting of aluminum foil; aluminum laminates; polyester laminate; polyester/aluminum laminates; paper; paper/aluminum laminates; and combinations thereof.
 10. The package of claim 1, wherein the lid sheet has a thickness ranging from about 12 microns to about 30 microns.
 11. The package of claim 1, wherein the reinforcing sheet comprises paper or paper/polymer laminates.
 12. The package of claim 1, wherein said reinforcing sheet has a thickness of about 0.7 mm to about 1.5 mm.
 13. The package of claim 1, wherein said ledge has a shape that is semi-circular and comprises a sharp edge.
 14. The package of claim 13, wherein the edge is serrated.
 15. The package of claim 1, further comprising an additional reinforcing sheet attached to said base sheet at a side opposite from the lid sheet, said additional reinforcing sheet comprising at least one additional cut-out section configured for accommodating said at least one depression therein.
 16. The package of claim 11, wherein said reinforcing sheet and said additional reinforcing sheet are formed by a single sheet that is folded over.
 17. A package for containing and dispensing at least one article, comprising: a) a base sheet having at least one depression formed therein for containing an article, the depression having an opening, wherein the base sheet has a depression thickness that is no more than ¾ of its base thickness; b) a lid sheet attached to said base sheet to cover the opening of said at least one depression; and c) a reinforcing sheet attached to the lid sheet at a side opposite from said base sheet, said reinforcing sheet having at least one cut-out section that overlaps with but offsets from the opening of said depression so that a portion of the reinforcing sheet forms a ledge near the opening of said depression for cutting the lid sheet and releasing the article from said depression.
 18. The package of claim 17, wherein the article is elastically deformable.
 19. The package of claim 18, wherein the ledge is sharp.
 20. The package of claim 19, wherein the package is a blister pack. 